Water generation from air utilizing solar energy and adsorption refrigeration unit

ABSTRACT

The invention is a water generator device from air utilizing solar thermal energy and adsorption principle. The system is based on an adsorption refrigeration unit with Ether as a refrigerant and activated carbon as adsorbed. The required heat is generated from evacuated tube solar system and the heat sink is the atmosphere. The adsorption unit is an air-cooled refrigeration unit that can operate at relatively low hot water temperature (60-70° C.) and relatively high atmospheric temperature (30-40° C.). The water condensed from air is than driven through a simple water purification unit to assure its quality as drinking water. The very small electricity needed to operate the hot water and cold water pumps along with the filtration unit and the controller of the adsorption unit is generated from a small Photo Voltaic (PV) unit for stand alone systems.

TECHNICAL FIELD

The present invention relates to a water generator system from airutilizing solar thermal energy and adsorption. The inventionspecifically concerns the system based on an adsorption refrigerationunit with ether as a refrigerant and activated carbon as adsorbent.

BACKGROUND OF THE INVENTION

The systems generate water from air are based on the passive desiccantadsorption principle. In these systems humid cold air is passed througha humidity adsorbent and then solar energy is used for repelling theadsorbed water into hot air to increase its humidity content. When thehumid air cooled to around atmospheric temperature, condensation occurs.Furthermore there are refrigeration units operating by electricity toprovide dehumidification of air. These units utilize the solar photonenergy of the sun but these systems are very expensive.

In prior art, some patent applications DE4430902, JP2004232998,RU2230858, U.S. Pat. No. 421,934 and US2005/103615 are known related tosubject. Hereafter, the present application and said prior art documentswill be compared. Since the documents DE4430902, JP2004232998,RU2230858, and U.S. Pat. No. 421,934 are of similar concept and theywill be evaluated together. However, US2005/103615 will be evaluatedseparately since it is of different concept.

The devices and systems in first group of patents (DE4430902,JP2004232998, RU2230858, and U.S. Pat. No. 421,934) are based on atotally different concept from the present invention. They all depend onthe passive desiccant adsorption principle. Their basic principle is topass humid cold air to a humidity adsorber (celiac gel or similarmaterials) and then utilize solar heat energy to repel the adsorbedwater into hot air hence increasing its humidity content. Later on thishumid air is cooled to around atmospheric temperature where condensationwould occur. Each patent uses different approach to do this but they areall based on the same basic principle. None of these patents uses anactive refrigeration unit to condense water directly from the air. Theoperating principle of all of these patents differs from the presentinvention by the following:

-   -   1—They all use desiccant adsorption techniques relying on        temperature difference between day and night. They do not use an        active refrigeration unit like present invention which is        independence on the temperature difference between day and        night.    -   2—In these patents, the air flows directly to the adsorber to be        dehumidified and then water is repelled from the adsorber        utilizing solar energy. In present invention air does not flow        into the adsorber but water is extracted from it by cooling it        below atmospheric temperature to a limit where condensation        occurs. The adsorption principle is applied to the refrigeration        unit which can also act as solar cooling unit with some        modification.    -   3—The water extraction by such techniques is limited since it is        bounded to cool humid air to atmospheric temperature only. The        present invention can cool air to sub-zero temperature hence        extracting large portion of its water content even for dry        weather.    -   4—The devices and systems those patents work on a day/night        intermittent cycle where water is generated either during the        day or during the night (or part of day and night). For example        the system in patent DE4430901 extracts water in night but        systems in other patents (JP2004232998, RU2230858, and U.S. Pat.        No. 421,934) extract water in day time. The present invention        extracts water day or night and at any suitable or needed time.    -   5—The operation of those patents is limited to low ambient        temperature at night and will not work efficiently for high        night temperature. The reasons is that desorption is an        exothermic process and adsorbent needs to be cooled during this        process. Hence, if air is of high temperature the process will        not occur. This is especially true for patents DE4430901 and        JP2004232998 where very cold air temperature at night is needed        while patents RU2230858 and U.S. Pat. No. 4,219,341 can operate        at moderate night temperature. The present invention, on the        other hand, can operate efficiently at ambient temperature of        40° C. day and night.

Unlike previously discussed patents, the device disclosed inUS2005/103615 uses an active refrigeration cycle with Ammonia andCalcium Chloride as the refrigeration pair. However, the cycle used inthis patent is an intermittent day/night cycle (i.e. condensation ofrefrigerant occurs during the day and evaporation occurs during night).Furthermore, the operation cycle in patent US2005/103615 is totallydifferent from the cycle in the present invention since it does not havea continuous cyclic operation and does not allow for regeneration ofresidual gas. The cycle in the previous patent is of low efficiency andneeds a very high heating temperature (120° C. or 250° F.) which theinventor can only obtain by using parabolic trough or concentrating dishsolar collector with tracking mechanism. Furthermore, such high degreeof hot temperature can only be obtained in a non-hazy or non-cloudy dayfor few period of the day.

In contrast to the device disclosed in US2005/103615, the presentinvention is based on a novel continuous operation adsorption cycle(condensation and evaporation of refrigerant occurs all day and night orwhenever needed) with two generators allowing adsorption and de-sorptionto occur continuously on consecutive manner. Here, ether-activatedcarbon refrigerant-adsorbent pair is utilized in a way that heatingtemperature as low as 60 C can be used. Such low temperature can beobtained by low cost evacuated tubes solar collectors even at hazy orlightly cloudy days and for all period of the day. The stored hot watercan be utilized day and night or whenever is most suitable to be usedwith continuous operation.

As such, the present invention is totally different in form and inprinciple from that of patent US2005/103615 and has the followingadvantage on it:

-   -   1—The present invention is based on continuous cycle operation        with high efficiency. The system disclosed in US2005/103615 is        based on day/night intermittent cycle with low efficiency.    -   2—The present invention needs hot water as low as 60° C. which        can be obtained with low cost evacuated tube solar collector at        various weather conditions. The system in US2005/103615 needs        heat at 120° C. (250° F.) which needs complicated parabolic        trough or concentrating dish solar collectors with complicated        tracking devices and operates only on shiny days for a portion        of the day only.    -   3—The present invention works efficiently at high ambient        temperature day or night (as high as 40° C.). The system in        US2005/103615 cannot work efficiently at high night ambient        temperature because the generator is insulated to allow its        temperature to reach 120° C. during day, but a complicated heat        dissipating mechanism is needed in the night to cool the        generator.    -   4—In the present invention, the solar collectors are not        affected much by wind and are of sturdy compact size. The        parabolic troughs or the concentrator dishes in US2005/103615        are very much affected by wind due to their large area and wind        can seriously affect their concentration point.    -   5—Simple controller is needed in for present invention while        complicated controller is needed for the device in US2005/103615        for tracking system, night cooling effect, and system operation.

BRIEF DESCRIPTION OF THE INVENTION

The invention is a method for water generation from air utilizing solarthermal energy and adsorption principle; and a system related to saidmethod. The system is based on an adsorption refrigeration unit withEther as a refrigerant and activated carbon as adsorbed. The requiredheat is generated from evacuated tube solar system and the heat sink isthe atmosphere. The adsorption unit is a novel air-cooled refrigerationunit that can operate at relatively low hot water temperature (60-70°C.) and relatively high atmospheric temperature (30-40° C.). The watercondensed from air is then driven through a simple water purificationunit to assure its quality as drinking water. The very small electricityneeded to operate the hot water and cold water circulation pumps alongwith the filtration unit and the controller of the adsorption unit isgenerated from a small Photo Voltaic (PV) unit for stand alone systems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the water generating system from air and all of itsmain components.

FIG. 2 illustrates an evacuated tube solar collector (E.S.C.).

FIG. 3 illustrates a system including a gas cycle, hot water cycle andcooling water cycle.

FIG. 4 illustrates a gas cycle of the system.

FIG. 5 illustrates a representation of the generator.

FIG. 6 illustrates details of the coaxial tubes of the generator.

FIG. 7 illustrates details of the end portions (inlet and outlet) of thegenerator.

DETAILED DESCRIPTION OF THE INVENTION

The invention comprises adsorption refrigeration unit based onEther-Activated Carbon as adsorbent-refrigerant pair. The gas cycle ofthe adsorption unit comprises two generators especially designed toallow high efficiency for sorption-desorption process at the desiredtemperatures. Adsorption of Ether into the activated carbon is activatedby cooling the generator via the cold water cycle with a regularradiator as heat sink. To cool the cold water below atmospherictemperature, a coil is located between the evaporator and the condenserwhich is also parts of the cooling cycle. The gas cycle also comprisestwo on-off valves (i.e., electrically controlled), two three-way valves,and one throttling expansion valve. An evacuated tube solar collectorwith storage tank and a heat exchanger coil inside provides the heatneeded for the hot water cycle. A simple low-power water filtration unitis utilized comprising five stages filtration process, a bump, and twostorage tanks. A small PV unit with PV panels, battery storage andregulation system provides the needed electricity of the system. Adigital controller is also part of the system needed to control the hotand cold water circulation pump along with the solenoid and three-wayvalves of the gas cycle.

The adsorption unit utilizes the thermal solar energy into cooling tocondense humidity from the air. The operation of its parts will beexplained later on. The evacuated tube solar system provides the hotwater for the adsorption unit. The radiator provides the heat sink ofthe system and cools down the cold water. The coil between theevaporator and the condenser lowers the cold water temperature belowatmospheric to increase the efficiency of the adsorption process. Thewater filter process the condensed water from the adsorption unit toeliminate any bacteria which might contain, filter the water, andmineralize it. The PV unit provides the needed little electricity tooperate the pumps and the fans and the valves for the system. Thecontroller coordinates the operation of pumps, solenoid valves, andthree-way valve to generate the needed sorption and de-sorption process.

The adsorption unit with all of its component and process is new to theinvention especially the utilization of Ether and activated carbon pairand the cycle itself. The conventional units are the PV electricityunit, the solar collector unit, the filtration unit and the controller.

For the purpose of system and cycle description this abbreviationexplains the symbols of the figures;

-   E: Evaporator-   E.V.: Expansion Valve-   E.S.C.: Evacuated Tube Solar Collector-   G1, G2: Generators-   N1, N2, N3, N4: Non-Return Valves-   PC: Cold Water Circulating Pump-   PH: Hot Water Circulating Pump-   S1, S2: On-off Valves-   R: Radiator-   3W1, 3W2: three way valves that allow either hot water or cold water    to enter the generators-   A.C.: Accumulation Chamber

The water generating system from air and all of its main components aredemonstrated in FIG. 1. However, the novel part of the system is theSolar Adsorption Dehumidification unit which will be described in fulldetails later. However, it is convenient to explain the components ofthe entire system to signify its operation.

Heat is generated by evacuated tube solar collector (E.S.C.). Thiscollector heats up the hot water needed for the adsorption unit andstores it to be used when suitable. There are many low cost modelsavailable in the market and FIG. 2 shows one of the models which allowwater to be heated by passing through a copper coil in the stored heatmedium. The adsorption unit is a heat operated refrigeration cycle thatwill be explained in details later. This unit needs a heat sink like allrefrigeration cycles according to the second law of thermodynamics andthis heat sink can be a simple radiator to dissipate heat to theatmosphere. The adsorption unit can cool air to very low temperatures(can go down to −5° C.) to condense the humidity in the air and toaccumulate that in a container. The humidified water is low with saltand needs little electricity to guarantee its drink-ability. It passesthrough a simple filtration process that utilizes UV to kill anybacteria that might exist in the condensed water, carbon to removeorganic contaminants that causes taste, odor and color problems fromwater, and mineralizing process. A relatively simple controller isneeded to control the operation of the adsorption unit and can beutilized also to monitor the best condition that suitable for operation.In desert arid area, for example, the solar collector can store heat allday and the system will operate during evening time where humidity andtemperature are more suitable for system operation. On the other hand,in hot and humid weather conditions the system can operate both day andnight continuously. Hence the controller can monitor the humidity andthe temperature of the atmosphere and start the dehumidifying processwhenever it is suitable. The controller can be a complicated (feed-back)operation that senses the temperature and the pressure of certainlocations in the cycle as will be described later or a timer basedcontroller if all conditions are known ahead.

Principle of Operation of the Adsorption Unit

To explain the principle of operation of the solar adsorption unit, thephysical phenomenon behind it and then the step by step operationprocedure will be described. After that a detailed description of thegenerator tank will be described.

Physical Phenomenon

Adsorption is a well know phenomenon. However, many tests were conductedand they showed that the activated carbon adsorbs Diethyl Ether (C₄H₁₀O)at atmospheric temperature (20-35° C.) and desorbs it at 60° C. orabove. In this invention, this phenomenon is utilized to generatepressure difference suitable to obtain cooling effect hence replacingthe compressor in the traditional refrigeration cycle. Basically thereare two generators that while one is cooled other is heated allowing forthis pressure difference and utilizing it to achieve main goal asdescribed after.

Briefly, in present invention, the system for water generationcomprises:

-   -   an adsorption unit, performing a heat operated refrigeration        cycle, for water generation by cooling air to condense the        humidity in the air and to accumulate that in a container;    -   a solar collector with evacuated tubes (E.S.C.) providing the        hot water for the adsorption unit;    -   a radiator (R), as a heat sink of the system, to dissipate heat        to the atmosphere; and providing cold water for the adsorption        unit;    -   a water filtration unit processing the condensed water from the        adsorption unit to eliminate any bacteria which might contain,        also filtering and mineralizing the water;    -   a hot water circulation pump (PH) for said solar collectors        (E.S.C.); a cold water circulation pump (PC) for said radiator        (R);    -   a controller unit of the system;    -   a source of electricity to operate the system.

The source of electricity can be any kind of electric supplier unit;however, it preferably comprises at least a photo-voltaic unit.

The adsorption unit, utilizing ether as refrigerant, of this systemcomprises;

-   -   two generators (G1, G2), filled with activated carbon as        adsorbent, and connected to each other by refrigerant flow line        where an on-off valve (S2) is located, said generators (G1, G2)        having hot water outlets connected to said circulation pump        (PH), cold water outlets connected to said circulation pump        (PC), hot and cold water inlets from two three-way valves, and        refrigerant inlets and outlets;    -   a condenser (C) unit firstly connected to a junction coming from        two refrigerant flow lines of non-return valves (N1, N2) which        are on outlets of the generators (G1, G2); secondly connected to        first on-off valve (S1) whose flow line extends to an expansion        valve (EV);    -   an evaporator (E) unit firstly connected to the expansion valve        (EV); secondly connected to a junction going to two refrigerant        flow lines of non-return valves (N3, N4) which are on the other        outlets of the generators (G1, G2);    -   a fan unit for cold air blowing from the evaporator (E) to the        condenser (C);    -   two three-way valves (3W1, 3W2) that allow either hot water or        cold water to enter the generators (G1, G2); first one (3W1) is        connected to first generator (G1), second one is (3W2) is        connected to second generator (G2); also both (3W1, 3W2) are        either connected to cold water line coming from the radiator (R)        or hot water line coming from the solar collector with evacuated        tubes (ESC);    -   a coil, between condenser (C) and evaporator (E), connected to        cold water line coming from the radiator (R); and connected to        said three-way valves (3W1, 3W2).

Here, the adsorption unit generates the water from the humidity in theair accumulated on the cooled outer surface of the evaporator (E), bymeans of the refrigeration cycle in adsorption unit.

Refrigeration Cycle Operation

To achieve cooling effect the cycle is basically composed of 3 closedloops cycle as shown in FIG. 3. The first is the gas cycle drawn insolid lines (with one step in a double solid line), the hot water cycledrawn in dotted line, and the cooling water cycle drawn in dashed line.The hot water is generated from the solar collector (E.S.C.) while thecooling water cools to atmosphere in the radiator R and cools more fromthe cold air getting out of the evaporator. The abbreviation for each ofthe components of FIG. 3 is given above. However, to make it easier forexplanation, only the gas cycle extracted and presented in FIG. 4.Firstly, the continuous cycle operation and then start up operation willbe explained.

Continuous Operation

The continuous operation for this refrigeration cycle is done in 6 stepsgoverned by the controller as follows.

Step-1—

In this step the first on-off valve (S1) is open and the second (S2) isclosed. The hot water pump (PH) and cold water pump (PC) are turned on,the first three way valve (3W1) allows hot water to flow to firstgenerator (G1) (initially filled with refrigerant, ether) while secondthree way valve (3W2) allows cold water to flow to second generator (G2)that is initially empty (or at low level) of Ether. Since, firstgenerator (G1) is pressurized above the atmospheric pressure (1.1-1.2bar absolute) due to heat, and then the refrigerant will be desorbedfrom the activated carbon and flow through the first non return valve(N1). The third non-return valve (N3) prevents the refrigerant fromflowing in the other direction and the second non-return valve (N2)prevents the refrigerant from going to second generator (G2) (since itis at vacuum) hence the refrigerant has to go to the condenser (C). Inthe process the refrigerant will condense in the condenser (C) due tothe low temperature of air flowing from the evaporator (E). Therefrigerant then flows through the expansion valve (E.V.) evaporates inthe evaporator (E) at low temperature depends on the level ofcondensation needed (up to −5° C. can be easily achieved). Gas will thenbe adsorbed in the second generator (G2).

To summarize this step gas flows from the first generator (G1) throughthe first non-return valve (N1) to the condenser (C) though the firston-off valve (S1) to the evaporator (E) through the fourth non-returnvalve (N4) to the second generator (G2).

The length of this step depends on temperature and size of unit. Thiscan be timed in the controller or a feed back controller which sensesthe pressure at each generator can be used. Air flows through theevaporator which condenses its humidity and lowers the temperature ofthe cooling water to improve adsorption efficiency.

Step-2—

The first on-off valve (S1) is closed, the second on-off valve (S2) isopen, and the pumps (PH, PC) are turned off. This is an intermediatestep to increase the efficiency of the cycle by moving residual gasesfrom the first generator (G1) to the second generator (G2) through thesecond on-off valve (S2) (double line path shown in FIGS. 3-4). Hence,the first generator (G1) is depressurized and cooled getting ready toadsorption, while the second one (G2) is pressurized and heated gettingready to the desorption process. This step takes time until pressure inboth generators (G1, G2) equalizes.

Step-3—

This also is an intermediate step in which both on-off valves (S1, S2)is closed, the pumps (PH, PC) are turned on, first three way valve (3W1)allows cold water and the second one (3W2) allows hot water. This steptakes time until pressure in the first generator (G1) is at vacuum level(0.2 bar absolute) and in the second generator (G2) is above theatmospheric pressure (1.2 bar absolute).

Step-4—

This step is opposite to step 1. The first on-off valve (S1) is open,the second (S2) is closed, the pumps (PH, PC) are turned on, firstthree-way valve (3W1) allows cold water and the second (3W2) allows hotwater. Gas flows from the second generator (G2) through the secondnon-return valve (N2) to the condenser (C), through the first on-offvalve (S1) to the expansion valve (E.V.) to the evaporator (E), throughthe third non-return valve (N3) to the first generator (G1).

Step-5—

Same as step 2 where the first on-off valve (S1) is closed, the secondon-off valve (S2) is open, the pumps (PH, PC) are turned off. Here,second generator (G2) gets depressurized and the first one (G1) getspressurized. So pressure is getting equal.

Step-6—

Opposite to Step 3, the first on-off valve (S1) is closed, the secondone (S2) is closed, the pumps (PH, PC) are turned on, the firstthree-way valve (3W1) allows hot water and the second (3W2) allows coldwater.

Then it is come back to step 1 and continued the cycle.

Start-Up Operation

At start-up both generators are at atmospheric temperature and of equalvacuum level (around 0.5 bar absolute). Before the continuous operationstarts with step 1 the following 2 steps must occur for one time only atstart-up.

Step-A—

Both on-off valves (S1, S2) are closed, the second three-way valve (3W2)allows hot water, the first (3W1) allows cold water to flow in, if coldwater pump (PC) is operated (or preventing hot water from flowing in);the hot water pump (PH) is turned on, the cold water pump (PC) is turnedoff, desorption occurs in (G2) releasing the gas from the activatedcarbon and increases the pressure in the condenser due to gas build upand heat.

Step-B—

Both on-off valves (S1, S2) are closed, the second three-way valve (3W2)allows cold water, the first (3W1) allows hot water, the hot water pump(PH) is turned on, the cold water pump (PC) is turned on, the secondgenerator (G2) gets cooled and depressurized getting ready to receivegas and the first generator (G1) is heated and is getting ready foradsorption.

Then it is come to step 1 in the continuous operation.

Briefly, in the present invention; three-way valves (3W1, 3W2) andon-off valves (S1, S2) are open and closed consecutively so that theadsorbent with the refrigerant in one of the two generators (G1, G2)release the refrigerant gas by heat from the collector (E.S.C.), therefrigerant enters condenser (C) via one of the non return valves (N1,N2) to get condensed and then flow into the expansion valve (E.V.) andsaid evaporator (E); while at the same time the other of two generatorsis cooled down so that adsorbent in it start the adsorption processwhich make the refrigerant in the evaporator (E) under go a phasetransition and absorb the heat from the passing humid air to effectcondensation of its humidity.

The on-off valves (S1, S2) are opened and closed consecutively so that amass transfer between the two generators (G1, G2) occur in anintermediate step to increase cycle efficiency; furthermore, the on-offvalves (S1, S2) are opened and closed at the start up of the system toreach a continuous operation procedure in short time.

DETAILED DESCRIPTION OF GENERATOR EMBODIMENT

The generator is group of coaxial tubes filled with activated carbon andimmersed in water reservoir allowing the carbon to heat and cool in aneffective and fast way. Also the generator allows the gas to be desorbedand be adsorbed at the larges possible contact area between gas andcarbon. The water content of this generator is as low as possible.

The tested design of the generator to achieve its goals is shown inFIGS. 5, 6, and 7. Each of the two generators contains of group ofcoaxial tubes (i.e., copper tubes) at a length suitable to neededcapacities. The FIG. 6 is the enlargement of section D1 from FIG. 5which gives the basic configuration of the generator. It is seen, fromthe FIG. 6, that the activated carbon (10) is filled between the innertube (11) and inner perforated tube (12) which is around the inner tube(11).

Also, there is an outer perforated tube (13) which is around the otherperforated tube (12). The outer tube (14) is used to cover the tubes(11, 12, 13) mentioned above. Between, the outer tube (14) and outerperforated tube (13), there exists another activated carbon (10) layer.The refrigerant gas (30) (ether) is passed through the gap between twoperforated tubes (12, 13). The water (20) flows through the inner tube(11) and around the outer tube (14). The activated carbon area is thinenough to allow good heat transfer between the walls of the inner andouter tubes (11, 14) and the carbon (10). Also, the gap betweenperforated tubes (12, 13) is small to allow gas to pressurize easily andto reduce the dead space for the gas. The tubes (11, 12, 13, 14) in thegenerator are thermally conductive.

FIG. 7 shows the enlargement of section D2 from FIG. 5. It representsthe end portions (inlet and outlet) of the generator. It shows themultiple gaps connected to a tube for refrigerant gas (30) flows andmultiple inner and outer tubes (11, 14) connected to a tube for water(20) flow in the generator. The said end portions are used to inlet andoutlet for gas and water flow in the generator. The end portions of eachgenerators contains an accumulation chamber (A.C.) of said refrigerant;the coaxial tubes forms heat transfer surface to cold or from hot waterflowing around the outer tube (14) and inside the inner tube (11).

1. A system for water generation from air comprising; an adsorptionunit, performing a heat operated refrigeration cycle, for watergeneration by cooling air to condense the humidity in the air and toaccumulate that in a container; a solar collector with evacuated tubes(E.S.C.) providing the hot water for the adsorption unit; a radiator(R), as a heat sink of the system, to dissipate heat to the atmosphere;and providing cold water for the adsorption unit; a water filtrationunit processing the condensed water from the adsorption unit toeliminate any bacteria which might contain, also filtering andmineralizing the water; a hot water circulation pump (PH) for said solarcollectors (E.S.C.); a cold water circulation pump (PC) for saidradiator (R); a controller unit of the system; a source of electricityto operate the system; said system is characterized in that theadsorption unit, utilizing ether as refrigerant, comprises; twogenerators (G1, G2), filled with activated carbon as adsorbent, andconnected to each other by refrigerant flow line where an on-off valve(S2) is located, said generators (G1, G2) having hot water outletsconnected to said circulation pump (PH), cold water outlets connected tosaid circulation pump (PC), hot and cold water inlets from two three-wayvalves, and refrigerant inlets and outlets; a condenser (C) unit firstlyconnected to a junction coming from two refrigerant flow lines ofnon-return valves (N1, N2) which are on outlets of the generators (G1,G2); secondly connected to an on-off valve (S1) whose flow line extendsto an expansion valve (E.V); an evaporator (E) unit firstly connected tothe expansion valve (E.V); secondly connected to a junction coming fromtwo refrigerant flow lines of non-return valves (N3, N4) which are onthe other outlets of the generators (G1, G2); a fan unit for cold airblowing from the evaporator (E) to the condenser (C); two three-wayvalves (3W1, 3W2) that allow either hot water or cold water to enter thegenerators (G1, G2); first one (3W1) is connected to the first generator(G1), the second one (3W2) is connected to the second generator (G2);also both (3W1, 3W2) are either connected to cold water line coming fromthe radiator (R) or hot water line coming from the solar collector withevacuated tubes (ESC); a coil, between the condenser (C) and theevaporator (E), connected to cold water line coming from the radiator(R); and connected to said three-way valves (3W1, 3W2) in that theadsorption unit generates the water from the humidity in the airaccumulated on the cooled outer surface of the evaporator (E), by meansof the refrigeration cycle in adsorption unit.
 2. A method according toclaim 1, wherein refrigeration cycle has a start-up operation in acondition that both generators (G1, G2) are at atmospheric temperatureand of equal vacuum level and said start-up operation comprises thefollowing steps where i. on-off valves (S1, S2) are closed, secondthree-way valve (3W2) allows hot water, first three-way valve (3W1)allows cold water to flow in, if cold water pump (PC) is operated (orpreventing hot water from flowing in); hot water circulation pump (PH)is turned on, cold water circulation pump (PC) is turned off, desorptionoccurs in the second generator (G2) releasing the gas from the activatedcarbon and increases the pressure in the condenser due to gas build upand heat; ii. on-off valves (S1, S2) are closed, second three-way valve(3W2) allows cold water, first three-way valve (3W1) allows hot water,hot water circulation pump (PH) and cold water circulation pump (PC) areturned on, the generator (G2) is cooled and depressurized getting readyto receive refrigerant and first generator (G1) is heated and gettingready for adsorption.
 3. A method according to claim 2, wherein, aftersaid start-up, refrigeration cycle has a continuous and repeatedoperation with the following steps; i. in the first step; the firstvalve (S1) is open and second valve (S2) is closed; the hot water pump(PH) and cold water pump (PC) are turned on, the first three-way valve(3W1) allows hot water to flow to generator (G1) (initially filled withrefrigerant) while second three-way valve (3W2) allows cold water toflow to the other generator (G2) that is initially empty (or at lowlevel) of refrigerant; since first generator (G1) is pressurized due toheat then the refrigerator will be desorbed from the activated carbonand flows through the first non return valve (N1); the third non-returnvalve (N3) prevents refrigerant from flowing in the other direction andsecond non-return valve (N2) prevents the refrigerant from going tosecond generator (G2) which is at vacuum, then the refrigerant goes tothe condenser (C) where the refrigerant condenses due to the lowtemperature of air flowing from the evaporator (E); then the refrigerantflows through the expansion valve (E.V.) evaporates in evaporator (E) atlow temperature depends on the level of condensation needed; finally therefrigerant will then be adsorbed in second generator (G2); ii. in thesecond step, the first on-off valve (S1) is closed, the second one (S2)is open, the pumps (PH, PC) are turned off to allow flowing of residualgases from first generator (G1) to second generator (G2) through thesecond valve (S2); and this step takes time until the pressure in bothgenerators (G1, G2) equalizes; iii. in the third step, both on-offvalves (S1, S2) are closed; the pumps (PH, PC) are turned on; firstthree-way valve (3W1) allows cold water and second three-way valve (3W2)allows hot water; and this step takes time until the pressure in firstgenerator (G1) comes to vacuum level, and pressure in second generator(G2) rises above atmospheric pressure; iv. in the fourth step; firston-off valve (S1) is open, second on-off valve (S2) is closed, the pumps(PH, PC) are turned on, first three-way valve (3W1) allows cold waterand second three-way valve (3W2) allows hot water; in this step therefrigerant flows from the second generator (G2) through the secondnon-return valve (N2) to the condenser (C), through the first one-offvalve (S1) to the expansion valve (E.V) to the evaporator (E), throughthe third non-return valve (N3) to the first generator (G1); v. in thefifth step, second step is repeated; vi. in the sixth step, both on-offvalves (S1, S2) are closed; the pumps (PH, PC) are turned on; firstthree-way valve (3W1) allows hot water and second three-way valve (3W2)allows cold water;
 4. A system according to claim 2; wherein the saidgenerator comprises a group of coaxial tubes filled with activatedcarbon and immersed in water reservoir allowing the carbon to heat andcool.
 5. A system according to claim 4; wherein the said generatorcomprises the activated carbon (10) which is filled between an innertube (11) and an inner perforated tube (12) which is around the innertube (11); an outer perforated tube (13) is around the other perforatedtube (12); an outer tube (14) which is used to cover the said tubes (11,12, 13); another activated carbon (10) layer between the outer tube (14)and outer perforated tube (13); an accumulation chamber (A.C.), for therefrigerant, at the inlet and outlet of the generator.
 6. A systemaccording to claim 5; wherein the refrigerant gas (30) is passed throughthe gap between two perforated tubes (12, 13); water (20) flows throughthe inner tube (11) and around the outer tube (14) in the generator. 7.A system according to claim 1; wherein the source of electricitycomprises at least a photo voltaic unit.